The present invention relates to novel 1,2,3,4-tetrahydroisoquinoline derivatives of the general formula I and their use as pharmaceuticals. The invention also concerns related aspects including processes for the preparation of the compounds, pharmaceutical compositions containing one or more compounds of formula I, and especially their use as orexin receptor antagonists.
The orexins (hypocretins) comprise two neuropeptides produced in the hypothalamus: the orexin A (OX-A) (a 33 aminoacid peptide) and the orexin B (OX-B) (a 28 aminoacid peptide) (Sakurai T. et al., Cell, 1998, 92, 573-585). Orexins are found to stimulate food consumption in rats suggesting a physiological role for these peptides as mediators in the central feedback mechanism that regulates feeding behavior (Sakurai T. et al., Cell, 1998, 92, 573-585). On the other hand, it was also proposed that orexins regulate states of sleep and wakefulness opening potentially novel therapeutic approaches for narcoleptic patients (Chemelli R. M. et al., Cell, 1999, 98, 437-451). Two orexin receptors have been cloned and characterized in mammals which belong to the G-protein coupled receptor superfamily (Sakurai T. et al., Cell, 1998, 92, 573-585), the orexin-l receptor (OX1) which is selective for OX-A and the orexin-2 receptor (OX2) which is capable to bind OX-A as well as OX-B.
Orexin receptors are found in the mammalian host and may be responsible for many biological functions such as pathologies including, but not limited to, depression; anxiety; addictions; obsessive compulsive disorder; affective neurosis; depressive neurosis; anxiety neurosis; dysthymic disorder; behaviour disorder; mood disorder; sexual dysfunction; psychosexual dysfunction; sex disorder; schizophrenia; manic depression; delerium; dementia; severe mental retardation and dyskinesias such as Huntington""s disease and Tourette syndrome; feeding disorders such as anorexia, bulimia, cachexia and obesity; diabetes; appetite/taste disorders; vomiting/nausea; asthma; cancer; Parkinson""s disease; Cushing""s syndrome/disease; basophil adenoma; prolactinoma; hyperprolactinemia; hypopituitarism; hypophysis tumor/adenoma; hypothalamic diseases; inflammatory bowel disease; gastric diskinesia; gastric ulcus; Froehlich""s syndrome; adrenohypophysis disease; hypophysis disease; pituitary growth hormone; adrenohypophysis hypofunction; adrenohypophysis hyperfunction; hypothalamic hypogonadism; Kallman""s syndrome (anosmia, hyposmia); functional or psychogenic amenorrhea; hypopituitarism; hypothalamic hypothyroidism; hypothalamic-adrenal dysfunction; idiopathic hyperprolactinemia; hypothalamic disorders of growth hormone deficiency; idiopathic growth deficiency; dwarfism; gigantism; acromegaly; disturbed biological and circadian rhythms; sleep disturbances associated with deseases such as neurological disorders, neuropathic pain and restless leg syndrome; heat and lung diseases, acute and congestive heart failure; hypotension; hypertension; urinary retention; osteoporosis; angina pectoris; myocardinal infarction; ischaemic or haemorrhagic stroke; subarachnoid haemorrhage; ulcers; allergies; benign prostatic hypertrophy; chronic renal failure; renal disease; impaired glucose tolerance; migraine; hyperalgesia; pain; enhanced or exaggerated sensitivity to pain such as hyperalgesia, causalgia, and allodynia; acute pain; burn pain; a typical facial pain; neuropathic pain; back pain; complex regional pain syndrome I and II; arthritic pain; sports injury pain; pain related to infection e.g. HIV, post-chemotherapy pain; post-stroke pain; post-operative pain; neuralgia; conditions associated with visceral pain such as irritable bowel syndrome, migraine and angina; urinary bladder incontinence e.g. urge incontinence; tolerance to narcotics or withdrawal from narcotics; sleep disorders; sleep apnea; narcolepsy; insomnia; parasomnia; jet-lag syndrome; and neurodegerative disorders including nosological entities such as disinhibition-dementia-parkinsonism-amyotrophy complex; pallido-ponto-nigral degeneration epilepsy; seizure disorders and other diseases related to orexin.
The present invention provides 1,2,3,4-tetrahydroisoquinoline derivatives which are non-peptide antagonists of human orexin receptors, in particular OX1 receptors. In particular, these compounds are of potential use in the treatment of obesity and/or sleep disorders.
So far not much is known about low molecular weight compounds which have a potential to antagonise either specifically OX1 or OX2 or both receptors at the same time. Recently WO 9909024 has been published wherein phenylurea and phenylthiourea derivatives as OX1 antagonists are disclosed. Also quite recently WO 9958533 has been published disclosing the same type of compounds which are again
described as being preferably OX1 receptor antagonists. The novel compounds of the present invention belong to an entirely different class of low molecular weight compounds as compared to all prior art orexin receptor antagonists so far published.
The present invention relates to novel 1,2,3,4-tetrahydroisoquinoline derivatives of the general formula (I). 
wherein:
R1, R2, R3, R4 independently represent cyano, nitro, halogen, hydrogen, hydroxy, lower alkyl, lower alkenyl, lower alkoxy, lower alkenyloxy, trifluoromethyl, trifluoromethoxy, cycloalkyloxy, aryloxy, aralkyloxy, heterocyclyloxy, heterocyclylalkyloxy, R11COxe2x80x94, NR12R13COxe2x80x94, R12R13Nxe2x80x94, R11OOCxe2x80x94, R11SO2NHxe2x80x94 or R14xe2x80x94COxe2x80x94NHxe2x80x94 or R2 and R3 together as well as R1 and R2 together and R3 and R4 together may form with the phenyl ring a five, six or seven-membered ring containing one or two oxygen atoms;
R5, R6, R7, R8, R9, R10 independently represent hydrogen, aryl, aralkyl, lower alkyl, lower alkenyl, trifluoromethyl, cycloalkyl, heterocyclyl or heterocyclyl-lower alkyl;
R11 represents lower alkyl, aryl, aralkyl, heterocyclyl or heterocyclyl-lower alkyl;
R12 and R13 independently represent hydrogen, alkyl, cycloalkyl, aryl, aralkyl, heterocyclyl or heterocyclyl-lower alkyl;
R14 represents alkyl, aryl, cycloalkyl, heterocyclyl, R12R13Nxe2x80x94 or R11Oxe2x80x94.
The compounds of formula I can contain one or more asymmetric centres and can be present in the form of optically pure enantiomers, mixtures of enantiomers such as, for example, racemates, optically pure diastereoisomers, mixtures of diastereoisomers, diastereoisomeric racemates, mixture of diastereoisomeric racemates, or meso forms and pharmaceutically acceptable salts thereof.
In the present description the term xe2x80x9clower alkylxe2x80x9d, alone or in combination, signifies a straight-chain or branched-chain alkyl group with 1 to 8 carbon atoms, preferably a straight or branched-chain alkyl group with 1-5 carbon atoms. Examples of straight-chain and branched C1-C8 alkyl groups are methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl, octyl, isobutyl tert-butyl, the isomeric pentyls, the isomeric hexyls, the isomeric heptyls and the isomeric octyls, preferably methyl, ethyl, propyl, isopropyl, butyl, 2-butyl, tert-butyl and pentyl.
The term xe2x80x9clower alkenylxe2x80x9d, alone or in combination, signifies a straight-chain or branched-chain alkenyl group with 2 to 5 carbon atoms, preferably allyl and vinyl.
The term xe2x80x9clower alkoxyxe2x80x9d, alone or in combination, signifies a group of the formula alkyl-Oxe2x80x94 in which the term xe2x80x9calkylxe2x80x9d has the previously given significance, such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy and tert-butoxy, preferably methoxy and ethoxy.
Lower alkenyloxy groups are preferably vinyloxy and allyloxy.
The term xe2x80x9ccycloalkylxe2x80x9d, alone or in combination, signifies a cycloalkyl ring with 3 to 8 carbon atoms and preferably a cycloalkyl ring with 3 to 6 carbon atoms. Examples of C3-C8 cycloalkyl are cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl, preferably cyclopropyl, cyclohexyl and particularly cyclohexyl or lower alkyl substituted cycloalkyl which may preferably be substituted with lower alkyl such as methyl-cyclopropyl, dimethyl-cyclopropyl, methyl-cyclobutyl, methyl-cyclopentyl, methyl-cyclohexyl, dimethyl-cyclohexyl,
The term xe2x80x9carylxe2x80x9d, alone or in combination, signifies a phenyl or naphthyl group which optionally carries one or more substituents, preferably one or two substituents, each independently selected from cyano, halogen, hydroxy, lower alkyl, lower alkenyl, lower alkoxy, lower alkenyloxy, nitro, trifluoromethyl, trifluoromethoxy, amino, carboxy and the like, such as phenyl, p-tolyl, 4-methoxyphenyl, 4-tert-butoxyphenyl 4-fluorophenyl, 2-chlorophenyl, 4-hydroxyphenyl, 1-naphthyl and 2-naphthyl. Preferred are carboxyphenyl, lower alkoxy-phenyl, hydroxyphenyl and particularly phenyl.
The term xe2x80x9caralkylxe2x80x9d, alone or in combination, signifies an alkyl or cycloalkyl group as previously defined in which one hydrogen atom has been replaced by an aryl group as previously defined. Preferred are benzyl and benzyl substituted in the phenyl ring with hydroxy, lower alkyl, lower alkoxy or halogen preferably chlorine. Particularly preferred is benzyl.
For the term xe2x80x9cheterocyclylxe2x80x9d and xe2x80x9cheterocyclyl-lower alkylxe2x80x9d, the heterocyclyl group is preferably a 5- to 10-membered monocyclic or bicyclic ring, which may be saturated, partially unsaturated or aromatic containing for example 1, 2 or 3 heteroatoms selected from oxygen, nitrogen and sulphur which may be the same or different. Example of such heterocyclyl groups are pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, pyridyl pyrimidinyl, pyrazinyl, pyridazinyl, quinolyl, isoquinolyl, thienyl, thiazolyl, isothiazolyl, furyl, imidazoyl, pyrazolyl, pyrrolyl, indazolyl, indolyl, isoindolyl, isoxazolyl, oxazolyl, quinoxalinyl, phthalazinyl, cinnolinyl, dihydropyrrolyl, pyrrolidinyl, isobenzofuranyl, tetrahydrofuranyl, dihydropyranyl. The heterocyclyl group may have up to 5, preferably 1, 2 or 3 optional substituents. Examples of suitable substituents include halogen, lower allyl, amino, nitro, cyano, hydroxy, lower alkoxy, carboxy and lower alkyloxy-carbonyls.
The term xe2x80x9chalogenxe2x80x9d signifies fluorine, chlorine, bromine or iodine and preferably chlorine and bromine and particularly chlorine.
The term xe2x80x9ccarboxyxe2x80x9d, alone or in combination, signifies a xe2x80x94COOH group.
A group of preferred compounds according to the present invention are compounds of formula (I) wherein R2, R3, R6, R7, R8 and R9 are hydrogen. Examples of preferred compounds are:
2-[1-(3,4-Dimethoxy-benzyl)-5,8-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-2-yl-methyl)-acetamide:
2-[1-(3,4-dimethoxy-benzyl)-8-(cyclopropyl-methoxy)-5-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-2-yl-methyl)-acetamide:
2-[1-(3,4-dimethoxy-benzyl)-8-(2-fluoro-ethoxy)-5-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-2-yl-methyl)-acetamide:
2-[1-(3,4-dimethoxy-benzyl)-8-(2,2-difluoro-ethoxy)-5-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-2-yl-methyl)-acetamide:
2-[1-(3,4-dimethoxy-benzyl)-8-ethoxy-5-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-2-yl-methyl)-acetamide:
2-[1-(3,4-dimethoxy-benzyl)-8-propoxy-5-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-2-yl-methyl)-acetamide:
2-[1-(3,4-dimethoxy-benzyl)-8-allyloxy-5-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-2-yl-methyl)-acetamide:
2-[1-(3,4-dimethoxy-benzyl)-8-isopropoxy-5-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-2-yl-methyl)-acetamide:
2-[1-(3,4-dimethoxy-benzyl)-5-propoxy-8-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-2-yl-methyl)-acetamide:
Another group of preferred compounds according to the present invention are compounds of formula (II) 
wherein:
Rxe2x80x21 and Rxe2x80x22 independently represent hydrogen, hydroxy, alkoxy, heteroaryloxy, carbamoyloxy or halogen or may form with the phenyl ring a five, six or seven membered-ring containing one or two oxygen atoms,
Rxe2x80x23, Rxe2x80x24, Rxe2x80x25 independently represent aryl, aralkyl, lower alkyl, lower alkenyl trifluoromethyl, cycloallyl, heterocyclyl or heterocyclyl-lower alkyl.
The compounds of formula (II) can contain one or more asymmetric centres and can be present in the form of optically pure enantiomers, mixtures of enantiomers such as, for example, racemates, optically pure diastereoisomers, mixtures of diastereoisomers, diastereoisomeric racemates, mixture of diastereoisomeric racemates, or meso forms and pharmaceutically acceptable salts thereof
Examples of preferred compounds of formula (II) are:
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-benzyl-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-naphthalen-1-ylmethyl-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(2-methoxy-benzyl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(4-fluoro-benzyl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(6-methoxy-naphthalen-2-ylmethyl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(4-methoxy-naphthalen-2-ylmethyl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(3,6)-difluoro-benzyl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(1-phenyl-ethyl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-3-ylmethyl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(2-methyl-benzyl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(3-methyl-benzyl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(1,2,3,4-tetrahydro-naphthalen-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-6-methoxy-7-(pyrazin-2-yloxy)-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-6-methoxy-7-(thiazol-2-yloxy)-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(5-methoxy-indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(6-methoxy-indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(6-methyl-indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(2-methyl-1,2,3,4-tetrahydronaphthalen-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(4-methyl-indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(6-methoxy-indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(6-methyl-indan-1-yl)-acetamide
2-{-[4-(pyrimidin-2-yloxy)-3-methoxy-benzyl]-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl}-N-benzyl-acetamide
2-[1-(3,4-dimethoxy-benzyl)-6-methoxy-7-(N,N-dimethylcarbamoyloxy)-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-(3-fluoro-propoxy)-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-(2-fluoro-ethoxy)-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-(2,2-difluoro-ethoxy)-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-(but-2-oxy)-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-(cyclopropyl-methoxy)-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-ethoxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-propoxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-allyloxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-isopropoxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-(1-methyl-prop-2-oxy)-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-benzyl-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-[(1S)-indan-1-yl]-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-benzyl-acetamide
2-[(1S)-1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin 2-yl]-N-[(1S)-indan-1-yl]-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-ethoxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-benzyl-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-propoxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-benzyl-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-allyloxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-benzyl-acetamide
N-benzyl-2-[1-(3,4-Dimethyl-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-acetamide
2-[1-(3,4-Dimethyl-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-[(1S)-indan-1-yl]-acetamide
N-benzyl-2-[-(3,4-Diethyl-benzyl)-6,7-dimethoxy-3,4-dihydro-H-isoquinolin-2-yl]-acetamide
2-[1-(3,4-Diethyl-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-2-yl-methyl)-acetamide
2-[1-(3,4-Diethyl-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-3-yl-methyl)-acetamide
2-[1-(3,4-Diethyl-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-4-yl-methyl)-acetamide
2-[1-(3,4-Dichloro-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-3-yl-methyl)-acetamide
Examples of particularly preferred compounds of formula (II) are:
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-benzyl-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-naphthalen-1-ylmethyl-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(1,2,3,4-tetrahydro-naphthalen-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-6-methoxy-7-pyrazin-2-yloxy)-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-6-methoxy-7-(thiazol-2-yloxy)-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(5-methoxy-indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(6-methoxy-indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(6-methyl-indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(2-methyl-1,2,3,4-tetrahydronaphthalen-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(4-methyl-indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(6-methoxy-indan-1-yl)-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(6-methyl-indan-1-yl)-acetamide
2-{1-[4-(pyrimidin-2-yloxy)-3-methoxy-benzyl]-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl}-N-benzyl-acetamide
2-[1-(3,4-dimethoxy-benzyl)-6-methoxy-7-(N,N-dimethylcarbamoyloxy)-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-(3-fluoro-propoxy)-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-(2-fluoro-ethoxy)-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-(2,2-difluoro-ethoxy)-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-(but-2-oxy)-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-(cyclopropyl-methoxy)-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-ethoxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-propoxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-allyloxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-isopropoxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(indan-1-yl)-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-(1-methyl-prop-2-oxy)-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-benzyl-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-[(1S)-indan-1-yl]-acetamide
2-[1-(3,4-Dimethoxy-benzyl)-6-methoxy-7-isopropoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-benzyl-acetamide
2-[(1S)-1-(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-[(1S)-indan-1-yl]-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-ethoxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-benzyl-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-propoxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-benzyl-acetamide
2-[1-(3,4-dimethoxy-benzyl)-7-allyloxy-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-benzyl-acetamide
N-benzyl-2-[1-(3,4-Dimethyl-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-acetamide
2-[1-(3,4-Dimethyl-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-[(1S)-indan-1-yl]-acetamide
N-benzyl-2-[1-(3,4-Diethyl-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-acetamide
2-[1-(3,4-Diethyl-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-2-yl-methyl)-acetamide
2-[1-(3,4-Diethyl-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-3-yl-methyl)-acetamide
2-[1-(3,4-Diethyl-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-4-yl-methyl)-acetamide
2-[1-(3,4-Dichloro-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-(pyridin-3-yl-methyl)-acetamide
Examples of physiologically usable or pharmaceutically acceptable salts of the compounds of formula (I) are salts with physiologically compatible mineral acids such as hydrochloric acid, sulphuric or phosphoric acid; or with organic acids such as methanesulphonic acid, acetic acid, trifluoroacetic acid, citric acid, fumaric acid, maleic acid, tartaric acid, succinic acid or salicylic acid. The compounds of formula (I) with free carboxy groups can also form salts with physiologically compatible bases.
Examples of such salts are alkali metal, alkali earth metal, ammonium and alkylammoniumsalts such as Na, K, Ca or tetraalkylammonium salt. The compounds of formula (I) can also be present in the form of a zwitterion.
The compounds of formula (I) can contain several asymmetric centres and can be present in the form of optically pure enantiomers, mixtures of enantiomers such as, for example, racemates, optically pure diastereoisomers, mixtures of diastereoisomers, diasteroisomeric racemates or mixtures of diastereoisomeric racemates and the meso-forms.
Preferred compounds as described above have IC50 values below 1000 nM; especially preferred compounds have IC50 values below 100 nM which have been determinated with the FLIPR (Fluorometric Imaging Plates Reader) method described in the beginning of the experimental section.
The compounds of the general formula (I) and their pharmaceutically usable salts can be used for the treatment of diseases or disorders where an antagonist of a human orexin receptor is required such as obesity, diabetes, prolactinoma, narcolepsy, insomnia, sleep apnea, parasomnia, depression; anxiety, addictions, schizophrenia and dementia.
The compounds of formula (I) and their pharmaceutically usable salts are particularly useful for the treatment of obesity and sleep disorders.
The compounds of formula (I) and their pharmaceutically usable salts can be used as medicament (e.g. in the form of pharmaceutical preparations). The pharmaceutical preparations can be administered internally, such as orally (e.g. in the form of tablets, coated tablets, dragxc3xa9es, hard and soft gelatine capsules, solutions, emulsions or suspensions), nasally (e.g. in the form of nasal sprays) or rectally (e.g. in the form of suppositories). However, the administration can also be effected parentally, such as intramuscularly or intravenously (e.g. in the form of injection solutions).
The compounds of formula (I) and their pharmaceutically usable salts can be processed with pharmaceutically inert, inorganic or organic adjuvants for the production of tablets, coated tablets, dragxc3xa9es, and hard gelatine capsules. Lactose, corn starch or derivatives thereof, talc, stearic acid or its salts etc. can be used, for example, as such adjuvants for tablets, dragxc3xa9es, and hard gelatine capsules.
Suitable adjuvants for soft gelatine capsules, are, for example, vegetable oils, waxes, fats, semi-solid substances and liquid polyols, etc.
Suitable adjuvants for the production of solutions and syrups are, for example, water, polyols, saccharose, invert sugar, glucose, etc.
Suitable adjuvants for injection solutions are, for example, water, alcohols, polyols, glycerol, vegetable oils, etc.
Suitable adjuvants for suppositories are, for example, natural or hardened oils, waxes, fats, semi-solid or liquid polyols, etc.
Morever, the pharmaceutical preparations can contain preservatives, solubilizers, viscosity-increasing substances, stabilizers, wetting agents, emulsifiers, sweeteners, colorants, flavorants, salts for varying the osmotic pressure, buffers, masking agents or antioxidants. They can also contain still other therapeutically valuable substances. The invention also relates to processes for the preparation of compounds of Formula I.
The compounds of general formula (I) of the present invention are prepared according to the general sequence of reactions outlined in the schemes below, wherein R1, R2, R3, R4, R5, R6, R7, R8, R10 are as defined in formula (I) above. As the case may be any compound obtained with one or more optically active carbon atom may be resolved into pure enantiomers or diastereomers, mixtures of enantiomers or diastereomers, diastereomeric racemates and the meso-forms in a manner known per se.
The compounds obtained may also be converted into a pharmaceutically acceptable salt thereof in a manner known per se.
The compounds of formula (I) may be prepared as single compounds or as libraries of compounds comprising at least 2, e.g. 5 to 1000 compounds of formula (I).
Compound libraries may be prepared by a combinatorial approach or by multiple parallel synthesis using solution phase chemistry.
For the combinatorial approach, the compounds of general formula (I) wherein R6, R7, R9 are hydrogen, are prepared using an Ugi-three-components-condensation reaction (Ugi-3-CC) which involves the one-pot reaction between a 1,2,3,4-tetrahydroisoquinoline derivative, an aldehyde and an isocyanide (Scheme 1). 
Isocyanides not commercially available might be prepared from the corresponding amines by N-formylation followed by treatment with POCl3 (see e.g. J. March, fourth edition, Wiley-Interscience publication, p. 1042).
The compounds of the general formula (I) wherein R6 and R7 are hydrogen, may also be prepared by different procedures. The synthetic route depends on the last chemical transformation which has to be carried out.
In all cases in which the coupling of the tetrahydroisoquinoline with the amide side-chain is the final step the standard procedure shown in (Scheme 2) was followed. The tetrahydroisoquinolines as well as the amines (R9R10NH) could be either commercially available or synthesized. 
Tetrahydroisoquinolines not commercially available might be prepared from the corresponding phenylethylamines by coupling with the desired carboxylic acid followed by treatment with POCl3 and finally NaBH4 (see experimental part). All aminoindan-derivatives were prepared by reaction of 1-indanones with O-methylhydroxylamine followed by reduction with borane-tetrahydrofuran complex (Vaccaro W. et al., J. Med. Chem., 1996, 39, 1704-1719).
Compounds of general formula (I) wherein one substituent of the 1-benzyl-tetrahydroisoquinoline scaffold is a carbamoyloxy-, heteroaryloxy- or alkoxy-residue (not methoxy) are synthesized according to (Scheme 3). The benzyl-protected phenols are prepared by the procedure shown in (Scheme 2). 
In the case R5 (general formula I) is a heterocyclyl-methyl substituent the final step is the substitution of a mesylate function with the corresponding nitrogen containing nucleophile according to (Scheme 4). The required starting material was synthesized by the same procedure as described earlier (Scheme 2). 
Stereochemically pure compounds of general formula I are obtained by kinetic resolution of the tetrahydroisoquinoline (Corrodi H., Hardegger E., Helv. Chim. Acta, 1956, 39, 889-897) and coupling of the pure enantiomer with the amide linker according to Scheme 2. Furthermore 2-[(1S)-1-(3,4-Dimethoxybenzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-N-[(1S)-indan-1-yl]-acetamide could also be obtained by crystallization of the diastereoisomeric mixture of the two 2-{1[R,S]-(3,4-Dimethoxybenzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl}-N-[(1S)-indan-1-yl]-acetamides from methanol.
Experimental Section
I. Biology
Determination of OX1 Receptor Antagonist Activity
The OX1 receptor antagonist activity of the compounds of formula (I) was determinated in accordance with the following experimental method.
Experimental Method:
Intracellular Calcium Measurements
Chinese hamster ovary (CHO) cells expressing the human orexin-1 receptor and the human orexin-2 receptor, respectively, were grown in culture medium (Ham F-12 with L-Glutamine) containing 300 xcexcg/ml G418, 100 U/ml penicillin, 100 xcexcg/ml streptomycin and 10% inactivated foetal calf serum (FCS).
The cells were seeded at 80,000 cells/well into 96-well black clear bottom sterile plates (Costar) which had been precoated with 1% gelatine in Hanks"" Balanced Salt Solution (HBSS). All reagents were from Gibco BRL.
The seeded plates were incubated overnight at 37xc2x0 C. in 5% CO2.
Human orexin-A as an agonist was prepared as 1 mM stock solution in methanol:water (1:1), diluted in HBSS containing 0.1% bovine serum albumin (BSA) and 2 mM HEPES for use in the assay at a final concentration of 10 nM.
Antagonists were prepared as 10 mM stock solution in DMSO, then diluted in 96-well plates, first in DMSO, then in HBSS containing 0.1% bovine serum albumin (BSA) and 2 mM HEPES.
On the day of the assay, 100 xcexcl of loading medium (HBSS containing 1% FCS, 2 mM HEPES, 5 mM probenecid (Sigma) and 3 xcexcM of the fluorescent calcium indicator fluo-3 AM (1 mM stock solution in DMSO with 10% pluronic acid) (Molecular Probes) was added to each well.
The 96-well plates were incubated for 60 min at 37xc2x0 C. in 5% CO2. The loading solution was then aspirated and cells were washed 3 times with 200 xcexcl HBSS containing 2.5 mM probenecid, 0.1% BSA, 2 mM HEPES. 100 xcexcl of that same buffer was left in each well. Within the Fluorescent Imaging Plate Reader (FLIPR, Molecular Devices), antagonists were added to the plate in a volume of 50 xcexcl, incubated for 20 min and finally 100 xcexcl of agonist was added. Fluorescence was measured for each well at 1 second intervals, and the height of each fluorescence peak was compared to the height of the fluorescence peak induced by 10 nM orexin-A with buffer in place of antagonist. For each antagonist, IC50 value (the concentration of compound needed to inhibit 50% of the agonistic response) was determined.
II. Chemistry
The following examples illustrate the preparation of pharmacologically active compounds of the invention but do not at all limit the scope thereof. All temperatures are stated in xc2x0 C.
All hydrochloride salts were prepared by dissolving the free-base in dichloromethane and treating with an excess of ethereal HCl (2M).
General Procedures:
A. General Procedure A:
1-[(3,4-Dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-acetic acid benzyl ester
To a white suspension of 1-(4,5-dimethoxybenzyl)6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline-hydrochloride (1 g, 2.632 mmol) in a mixture of toluene/DMF (9/1) (10 ml), were added triethylamine (1.1 ml, 7.896 mmol) and chlorobenzylacetate (440 xcexcl, 2.895 mmol). The reaction mixture was stirred at reflux under argon for 20 h. After cooling, the mixture was diluted in CH2Cl2 and washed with water.
The aqueous phase was extracted twice with CH2Cl2, the combined organic phases were dried over anhydrous MgSO4, filtered and concentrated to give a crude brown-orange oil. Flash chromatography (AcOEt/hexane 1/1) gave 1.15 g (89%) of the title product as a brown-orange oil.
TLC (AcOEt/hexane: 1/1): Rf=0.55.
LC-MS (MeCN/H2O: 1/1): Rt=4.16 min. m/z=492 (M+1).
1-(3,4-Dimethoxybenzyl)-6,7-dimethoxy-(3,4-dihydro-1H-isoquinolin-2-yl)-acetic acid.
To a solution of 1-[(3,4-dimethoxy-benzyl)-6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl]-acetic acid benzyl ester (1.15 g, 2.34 mmol) in dry AcOEt (20 ml) was added in one portion Pd-C 10% (250 mg). The resulting black suspension was hydrogenated at normal pressure and room temperature for 20 h. The mixture was then filtered over celite and concentrated in vacuo to give brown crystals.
LC-MS (MeCN/H2O: 1/1): Rt=3.34 min. m/z=402 (M+1).